The goal of our proposed research is the ascertainment of those properties of ventromedial region of the hypothalamus through which this region exerts its influence on the adjustment of food intake to fluctuating energy expediture; the result is that when the animal feeds spontaneously weight is maintained within narrow limits. The recognition of the importance of the ventromedial hypothalamus in the regulation of food intake makes available a rational approach to the problems of weight control and obesity. We have found that some of the cells in the ventromedial hypothalamus respond to inhibitors of glucose transport, to insulin and to hormones of the adrenal cortex and pituitary. We have found that the influence of these factors on the ventromedial hypothalamus and on feeding behavior are reflected in the susceptibility or resistance of specific glucoreceptor cells of this region of the brain to gold thioglucose-induced necrosis. We have established that the specific gold thioglucose-sensitive gluco-receptors of the ventromedial hypothalamus contain serotonin, a substance known to be involved in the functional activity of some portions of the central nervous system. Brain serotonin has been implicated in the regulation of feeding behavior. We are presently studying the relation of serotonin of the ventromedial hypothalamus to food intake and to metabolic processes.